Present security systems typically utilize some type of video surveillance. These video surveillance systems can be both active and/or passive. In active systems, a security person is employed to view a plurality of displays and alert the appropriate authorities in the event that suspicious activity occurs in the display. These can be of two types, a constant monitoring system wherein the individual views all displays simultaneously, a system wherein the individual continually views one monitor and switches to different remote cameras, or a system wherein security personnel periodically activate remote cameras and send the images over a phone line in a "freeze frame" format. In a passive system, a VCR is disposed at the remote location and is operable to record slow motion video by only recording certain frames. These are typically found in banks or other financial institutions. This allows security personnel at a later time to view the tapes if something has occurred.
One of the problems with passive video surveillance systems is that an individual must be employed full time to view the monitors and, further, that individual must be alert. For the substantial portion of the time that the individual is viewing the monitors, little is happening. As such, such devices referred to as "scene change monitors" have been employed to compare one video frame with another and determine if there has been a change in the frames. However, these scene change monitors have one disadvantage in that they are very memory intensive. They must store an entire video frame in what is referred to as a "frame buffer" and then compare frame buffers on a pixel-by-pixel basis. If the accumulated change over the frames stored in the frame buffer is great in accordance with a predetermined algorithm, this can set off an alarm.